1. Field of Invention
The present invention relates to an extract for preventing or treating thrombotic diseases, and more particularly to an extract of leech and/or earthworm with molecular weight of less than 5,800 Dalton, and pharmaceutical composition, processes for preparation and use thereof.
2. Description of Related Arts
As a kind of classic drug of removing blood clot, the Chinese Pharmacopeia records three kinds of leech Whitmania pigra Whitman, Hirudo nipponica Whitman and Whitmania ac-ranulata Whitman. Among them, Whitmania pigra Whitman is the most widely-used for drug. The main ingredients of leech are protein, polypeptide, amino acids, nucleic acid, enzyme, sugars, trace elements and etc. The qualitation and quantitation researches about ingredients in leech have been reported for many times. The main methods are TLC, HPLC, and electrophoretic method. The main micromolecular ingredients in leech are hypoxanthine, xanthine, uracil, uracil riboside and etc. Both Pyrimidine and Purine are unsaturated heterocyclic compounds containing N atoms.
As Chinese traditional medicine, earthworm in the Chinese Pharmacopeia has effects of clearing away heat, calming, getting through arteries and veins, smoothing breathe and diuretic. There are four kinds of earthworm in the Chinese pharmacopeia. They are Pheretima aspergillum (E. Perrier), Pheretima vulgaris Chen, Pheretima guillelmi (Michaelsen) and Pheretima pectinifera Michaelsen. Among them, Pheretima aspergillum (E. Perrier) also known as Lumbricus is the most widely-used for drug. The main ingredients in earthworm are protein, amino acids, nucleic acid, enzyme, sugars and etc. The qualitation and quantitation researches about ingredients in earthworm have been reported. The main micromolecular ingredients in earthworm are hypoxanthine and compounds containing N atoms.
Extracts of leech and earthworm is the active components in Shuxuetong Injection which possesses high performance and immediate effect in treating cardiovascular and cerebrovascular diseases. Chinese patent applications 03148281.3, 200410101538.8 and 200510000266.7 disclose Shuxuetong Injection and processes for preparation thereof respectively. All content of the applications were referred in the present invention.
Materials possessing immunogenicity often are macromolecule, and the larger molecular weight, the better the immunogenicity. Polypeptides with micromolecule often have no or few immunogenicity. Antigens often are macromolecule because the following probably reasons: (1) The relative molecular weight of antigens are bigger, the superficial Specific chemical genes are more, so that the effect of stimulating immunologic cells is better and the immunologic response is stronger; (2) Macromolecular antigens having complex chemical compositions and stable structures can not be destroyed and eliminated easily and can stay in human being's bodies for long time. So they can stimulate immunologic system persistently and immunologic response emerges. Insulin human composed of 51 amino acids (standard molecular weight is 5800 Dalton) is the boundary of distinguishing high molecular weight materials with low molecular weight materials. The high molecular weight materials are controlled strictly in injection.